The woman apparently used to work at the Tettau, Bavaria manufacturing plant for the cotton swabs used in the police investigations connected with the crimes, the paper said.

The case has developed into a major embarrassment for police in recent weeks when it emerged that the profile of the “Phantom Killer,” also known as “the woman without a face,” was based on faulty forensic procedures, where swabs not designed for crime scenes were used to collect evidence in several states. But this brand of cotton swab was consistently sold to state criminal investigation offices in Germany and Austria.

The DNA was connected to some six murders, including that of 22-year-old police officer Michele Kiesewetter in Heilbronn in 2007. The suspect was considered to be dangerous and brutal, baffling law enforcement by leaving tiny traces of her DNA at crime scenes over the course of 15 years within Europe.

Authorities had already suspected the possessor of the mysterious DNA was of Eastern European origins.

Apparently the cotton swabs were contaminated with traces of her genetic code years ago, and it remains unclear how this occurred at the factory, the source told the paper.